The green alga Ulva lactuca as a potential ingredient in diets for juvenile white spotted snapper Lutjanus stellatus Akazaki

Abstract

This trial evaluated the green alga Ulva lactuca as a potential ingredient in diets for juvenile white-spotted snapper Lutjanus stellatus Akazaki (initial mass 12.10 ± 0.10 g). Five test diets had similar protein and lipid levels (42 % crude protein and 8.5 % crude lipid), control diet without U. lactuca meal, four diets were added 5, 10, 15, and 20 % U. lactuca meal to investigate the effects of U. lactuca on growth performance, carcass composition, and enzyme activities of the fish. Each diet was assigned to triplicate groups of 30 fish for 60 days in 15 floating sea cages. At the end of feeding trail, final body weight (FBW), weight gain (WG), specific growth rate (SGR) of the fish fed 5 % UL diet were significantly higher than that of 10 and 20 % groups (P < 0.05). Pepsin activities in the stomach were significantly suppressed for the fish received 20 % U. lactuca diet (P < 0.05), lipase activity in stomach and intestinal decreased with increasing U. lactuca inclusion level in diet. The enzyme activities of aspartate amino transferase (AST) in liver and alanine amino transferase (ALT) in serum increased significantly from 5 to 20 % U. lactuca level (P < 0.05). These results indicate that incorporation of the U. lactuca in the diet at 5 % for juvenile white spotted snapper does beneficial effects on the growth performance but higher level of incorporation reduce fish performance and physiological state.